Manufacture of elastic stop nuts



Feb.- 9, 1937. c. A. SWANSTROM MANUFACTURE OF ELASTIC S TOP NUTS 2 s eets-siest- 1 Filed April so, 1955 1937: c. A. SWANSTROM ,0

Filed April 30, 1935 Patented Feb. 9, A 1937 UNITED" STATES,

PATENT, OFFICE.

MANUFACTURE OF ELASTIC STOP NUTS Application April 30, 1935, Serial No. 19,050

'16 Claims.

The present invention relates to the manufacture of elastic stop nuts and hasparticular reference to the manufacture of nuts of the kind shown in U. S. Pat. No. 1,550,282, granted to Ture Gustaf Rennerfelt on the 18th day of August,

In nuts of this character, which are self-locking, a non-metallic washer, preferably of pressed of the nut so that there is no possibility of the Washer turning, and further the diameter of the bore of the washer must be held within close 2o limits if satisfactory action-of the nut is to be obtained.

In nuts of the kind under consideration, the bore of the non-metallic washer is not threaded and the locking thread is formed in the washer by the thread of the bolt or stud on to which the nut is threaded. I have found that a most satisfactory action is obtained when the initial bore of the washer is of a diameter such that when the nut is threaded on to a bolt or stud of the proper size, the thread which is formed in the washer is from 60 to 80% of the full depth of the thread. If'it is less than this, the holding action of the washer is impaired, and if it is greater than this there is likelihood of,a part of the material of the washer being forced. out of the nut because of the excessive displacement of the material resulting from the formation of a full depth thread.

As a general rule it may be said that the larger the diameter of the bore of the nut the smaller non-metallic washer which in all cases is lockedwith suflicient pressure to eliminate possibility of turning within the nut andwhich, further, is

V 35 accurately dimensioned with respect to its inis the percentage of the full depth of thethread required to be formed in the washer to secure the ternal b'ore. To this end I first form a threaded nut blank having a washer-receiving recess at one end of the bore of the nut and anannular flange portion surrounding the recess. 'A washer of suitable fibrous material which is advantageously punched from strip or sheet material in known manner is then inserted into the recess and the annular flange crimped inwardly over the top of the washer to lock the washer in place, in the following manner. A pilot having a diameter slightly larger than the final diameter desired in the finished product is passed through the bore of the washer. before deforming or crimping pres sure is applied to the metal of the flange, and while the pilot is still retained within the washer and maintaining its bore at oversize diameter, the material of the flange is'crimped over the top of the washer to lock the washer in place. After the crimping operation is performed, the pilot is then withdrawn. Advantageously the bore in the washer blank is slightly less than the diameter of the pilot although this is not essential in all cases.

This series of steps, while capable of being performed by hand operations, is most advantageously carried out by means of a hand or power press, the latter being preferable from the standpoint of speed of production. When car,- ried out by means of a press having a certain stroke, provision must be made to take care of variations in the depth of the nut blanks, since a variation of a few thousandths of an inch wouldbe suflicient to cause a wide variation in the amount of locking pressure exerted on the washer.

In order to provide for uniform locking pressure in spite of such variation, and further in order to provide for the rapid and accurate manufacture of the nuts, I provide a novel form of .tool suitable for use in a press of ordinary known con struction, and further provide resilient means for supporting the nut during the pressing operation as will hereinafter be more fully described.

For a better understanding of the detailed nature of the invention and the manner in which nut blank;

Fig. 3 is a section taken on the line 3-4 of Fig. 4 is a section taken on the line H of Fig. 1;

Fig. 5 isa section taken on the line 6-4 of Fig. 2;

Fig. 6 is a side view of part of the apparatus;

Fig. 7 is a front view of the apparatus shown in Fig. 6;.

Fig. 8 is a section showing a different form of 'bedplate from that shown in Fig. 1; V

Fig. 9'is a section on an enlarged scale a stop the finished stop punch press having a press bed I! and standards Fig. 10 is a similar section of .nut; and

J2 and II carrying a slide it which is connected ther provided with a transverse enlarged head 42.

lower face ofthe slide. At end the head I! of the holder is provided with a at its lower end through by means of a pitman II to the crank arm 2| of a crank 22 which may be operated either by hand orfrom a suitable source of power. As shown in Figs. 3 and 5, the slide it is guided in suitable grooves 24 and 28 in the standards of the press. Slide "is in two parts. having a removable cap l6a adapted to be secured to the main part of the slide by means of studs 28.

slot II in which there is placed a knock-out bar 32, the bar being somewhat narrower than the slot and preferably being resiliently held against the upper edge of the slot by means of coil springs 34 attached to the standards. Adjustable studs I8 screwed into suitable bosses on the standards and held in adlusted position by suitable lock nuts are provided to force the knock-out bar away from the upper edge of the slot as the slide rises in'the press on its return from a working stroke.

The apparatus thus far described is of known construction, and present invention.

As shown in Figs. 3 and 5, the Ila are each provided with a semi-cylindrical recess which together form a cylindrical bore for clamping into the slide. a tool comprising a holder indicated generally at 38 and having a shank 40 adap ed to fit into Head 42 seats against the its lower or working cylindrical recess and at the center of the bottom of the recess there is fixed in the holder a pilot 4' which projects beyond the tool holder and is provided with a cylindrical pin-like end 48 I which advantageously terminates in a hemispherical surface. An annular punch N surrounds thepilot 4i and is provided with a bore I! which the pin portion of the pilot is adaptedto pass. At the upper end of the punch lo a cylindrical head Ii is provided.

which fits the bore of the recess 44. The recess-is on the lower end of the head 42 and between this cap or cover screwed cover and the shoulderjformed bythe head Iii there is located a spring which tends to keep the punch retracted as far as possible within the recess with the head I I in contact with the bottomoftherecess.

The shank u of the holder-"Ills provided with Tbores throushslhich D are in alignment as shown in 5 with the knockout bar. and are adapted to project into from the bottom of the H formed below The slide is fill"- per se forms no part of the slide is and cap" the bore of the slide and an the recess 44 to force the head of the punch away recess. The lower or working face of the punch is formed, as 'is more clearly shown in Fig. 11, to provide a generally conical recess 60, there being a downwardly'pro-' lecting lip 62 at the perimeter of the bore in which the pilot-pin II is situated.

Referring again to Fig. 1, the press bed It is advantageously recessed as at II to receive a re.- siliently mounted press bed member comprising a plate portion 64 and a stud extending through the press bedto the lower side. where it is held by a nut 88. In the recess below the plate member 64 there is a resilient bed III, of rubber. or the like, which is maintained under a predetermined compression pressure by means of adjustment of the nut i8.

For very heavy work, where high pressure under the plate 64 is desired, pneumatic means may advantageously be employed. and in Fig. 8

there is shownmore or less diagrammatically an arrangement of this sort comprising a cylinder the press bed and having in it a piston 12 which is'attached to the lower end of the stud portion 66 of themes bed member.

Air or other compressible fluid medium is supplied to the chamber of the cylinder II at predetermined pressure through a supply pipe "in com- I munication with any suitable-source of fluid pressure. I I i 'The operation ofthe apparatus thus far described ls as follows: by means of suitable feeding mechanism, which may be of any known form of construction and which, for the sake of clarity.

hasbeen omitted from the drawings, or by hand, anut blank I! of the form shown in Fig. 9 is fed to a position in the press in direct alignment with the pilot 46. As shown in Fig. 9. the nut'blank comprises a threaded body portion having a recess II at the upper end of the bore, in which recess there isv assembled in non-metallic washer-8|. The washer II, is somewhat thinner than the depth of the recess, so that the upper edge of the I walls of the the figure. 7

It will be understood that for the purpose of describing and claiming the present'invention I use the term washer in a broad sense and intend to include within the meaning of this term any annular locking member which may be of integral or laminated form. v

Assuming the press to be at the top of its stroke as. shown in Pig. 2, the downwardmovement of the slideon its out bar to move into contact of slot )0. This-permits head of the punch to the the toolholder so thatjhe pilot pin 0 projects beyond the working face of the punch. Further, in this position the head of the punch is seated solidly against the bottom of the recess in the tool holder prior to contact of the punch with the nut blank. with the parts in this relative position, the pin 48' enters and passes through the bore of the washer ll. Ble d-Rel. and with the pilot in the bore of the washer, the conical working face of the punch contacts the upper face of the. nut blank and deforms the upper edge of the recessed walls of the blank by turning them inrecess-project above it as shownin 'wardly and downwardly over the washer. the metal of the biankbeing deformedto the'iorm shown in Fig. 10. The deformationof the metal of the blankis obviously efl'ected by and pressure of the punch on the and in .order to secure the 7 5 I aova'osa washer in the blank with a predetermined locking pressure the resilient press bed member is provided.

It will be evident that in production manufacture, it is substantially impossible to hold the thickness ofthe nut blanks to exact limits, and it will further be evident that a variation of a few thousandths of an inch in the thickness of the blanks will, in a fixed stroke press, make a very substantial difference in the locking pressure applied to the washer upon deformation of the blank, if-the blank is resting on a'bed having a fixed distance with respect to the end point of the working stroke of the punch.

By substantial pre-compression of the resilien material under the movable press bed member or by use of compressed fiuid of substantial pressure, suflicient resistance to movement of the press bed member may readily be obtained to enable the required amount of deforming pressure to be applied by the punch.

The deformation of the walls of the blank inwardly and downwardly will evidently tend to compress the washer radially toward its center as well as downwardly, and this inward deforming or crimping pressure serves to force the washer against the sides of the pilot member.

The usual material for the locking washer is compressed fiber of known kind, and I have discovered that the most satisfactory results are obtained by making the diameter of the pilot pin somewhat larger than the desired final diameter of the bore of the washer, since when the pilot is removed from the bore the compression force exerted on the washer causes the diameter to decrease. By using a pilot during the deforming operation, I find it possible to hold the final bore of the locking washer to very close limits for the desired value.

On the return stroke of the slide, the frictionbetween the compressed washer and the pilot causes the ,nut to be lifted from the press bed with the pilot until the knock-out bar 32 comes in contact with the studs 36. Further movement of the slide on its return stroke then causes the knock-out bar to be moved from the position in the slot 30 shown in Fig. l to the position shown.

in Fig. 2, and this movement, through the pins 58, causes the punch to be moved relative to the holder and the pilot to a position as shown in Fig. 2, wherein the pilot is wholly retracted within the bore of the lower end of thepunch. This action serves to strip the nut from the tool, which is then ready for a repetition of the operation on a succeeding nut blank which has been placed in proper position during the return s oke. In order to prevent the nut, when stripped from the tool, from falling into a position interfering with the next working stroke of the punch; means is provided for knocking the stripped nut laterally from the path of reciprocation of the slide. This means is shown in Figs. 6 and 7, and comprises a cam plate 82 secured to slide I6 and contacting a pivoted lever 84 mounted on the standard I 4 and. having an arm 85 arranged to'knock the finished nut 88 laterally away from the tool as.

the latter reaches the position where the nut is stripped. On the working stroke, the arm 86 is It will be evident that tool apparatus of the above described character provides numerous adpunch and pilot permits ready interchange of tool parts suitable for different sizes of nuts. The

arrangement further permits free rotational.

movement of the punch in the holder, thus minimizing and equalizing wear. The spring which seats'the punch firmly in the holder before the punch comes in contact with the blank, prevents destructive slamming of the punch against the holder, and the large area of the punch head also minimizes wear. For the best results, the punch should be of hardened material and the pilot of a relatively soft and ductile material.

It will be evident that many changes and variations in the specific form of the apparatus herein disclosed may be resorted to without departing from the invention, the scope of which is to be understood ,as embracing all that falls within the terms of the appended claims when they are construed as broadly as is consistent with the state of the prior art.

2. In the manufacture of elastic stop nuts from blanks having an open-ended recess and a nonj metallic washer assembled therein, the improvement which consists in maintaining the diameter of the bore of the washer larger than the desired final diameter by inserting through'the bore of the washer a pilot member having' a diameter larger than said final diameter, deforming the walls of the recess inwardly over the top of the washer to lock the washer in said recess while said pilot membe'ris inserted through said bore and thereafter withdrawing said pilot member.

3. The method of forming an elastic stop nut from a stop nut blank having a recessed bore larged diameter of the boreof the washer.

4. The method of forming an elastic stop nut from a stop nut blank having a recessed bore and a non-metallic locking washer in said bore which consists in enlarging the initial diameter of the bore of the washer to a size larger than the desired final diameter, locking the washer in the recess by deforming the walls of the recess inwardly over the top of the washer due' to end pressure applied to the blank while maintaining said enlarged diameter of the bore of the washer and resiliently supporting said blank while applying said end pressurewhereby to, secure said locking washer inthe blank with predetermined pressure. 1

5. In apparatus for the'manufacture of elastic stop nuts of the kind having a non-metallic lock in'g washer incorporated therein, a pilot for determining the final diameter of the bore of the washer and a punch movable with respect to said pilot for deforming the side walls of the nut blank a washer'zincorporated therein, a tool comprising a 4 around the washer to lock it in the nut while said pilot is in said bore.

6. In apparatus for the manufacture of elastic stop nuts of the kind having a non-metallic looking washer incorporated therein, a pilot having a-diam'eter greater than the initial diameter of the bore of the washer, -means for forcing said pilot through'the washerand a punch movable with respect to said pilot for deforming the side walls of the nut blank around the washer to lock it in the nut while said pilot is in said bore.

7. In apparatus for the manufacture of elastic stop nuts of the kind having a non-metallic looking washer incorporated therein, a tool comprising a holder adapted tobe mounted in the slide of a press, a pilot fixed in said holder for de-. termining the final diameter of the bore of said washer, and a punch reciprocably mountedin said holder for turning the side walls of a nut blank inwardly and downwardly over said washer while said pilot is in the bore of the washer.

8. In apparatus for the manufacture of elastic stop nuts of the kindhaving a non-metallic locking washer incorporated therein, a tool oomprising a holder adapted to be mounted in the slide of a press, a recess in said holder, a pilot fixed in the holder andexten'dingtherefrom for determining the finaldiameter of the bore of said washer, an

annular punch for deforming the walls of the nut to lock the washer in place, said punch surrounding said pilot and having a head reciprocably mounted in said recess and a spring for resiliently holding said head in contact with the bottom of said recess;

9. In apparatus for the manufacture .of elastic stop nuts of the kind having a non-metallic washer incorporated therein, a tool' comprising a holder adapted to be mountedin the slide of a press,

a pilot fixed in said holder for determining the final inside diameter of the bore of said washer.

a recess in said holder, an annular punch for deforming the walls of the nut to lock the washer in place, said punch surrounding said pilot and having a head reciprocably mounted in said holder and a spring in said recess for holding said head in contact with the bottom of the recess, said pilotextending beyond the end of the bore of-the working .end of said punch when said head is seated in said recess.

10. In apparatus for the manufacture of elastic stop nuts of the kind having a non-metallic washer incorporated therein, a .tool comprising a holder adapted to be mounted in the slide oi a press, a recess in's'aid holder, a pilot fixed in the holder and extending therefrom for dete the final diameter of the bore of said washenan" annular punch for deforming the walls of the nut to lock the washer in place, said punch surrounding said pilot and having a head reciprocably mounted in said holder, a spring in said recess for holding said head in contact with the bottom of the recess, said pilot extending beyond the end of the bore of the working end of said punch when saidhead is seated in recess, and

means for forcing said punch away from its seat in said holder to a position with sdid pilot re- Y tracted within the bore of the operating end of the punch. I 1

its

11.v In apparatus for the manufacture of elastic stop nuts of .the kind having a' non-metallic holder having .a cylindrical recess, a pilot fixed in the holder and extending-therefrom coaxialiy of the recess, an annular punch slidably mounted aroundsaid pilot and having ahead reciprocable -s,o7o,os2

in said recess; an annular cover for closing said recess, a spring located in said recess between said cover and said head and acting to seat said head in the bottom of the recess, andaplurality of pins extending through the body of saidholder' and contacting said head for moving said punch outwardly of the holder. i

12. A tool for securing locking washers in elassecuredin the slideof a punch press, a pilot fixed in said holder and adapted to pass through the bore of the washeron the working stroke of the press, a punch .reciprocably mounted in said holder and having a working face for deforming the side walls of the nut inwardly and downwardtic stop nuts comprising a holder adapted to be ly around'said washer on the working stroke of the press after the pilot has passed through the bore of the washer, whereby to compress the washer inwardly against the pilot and to, cause the nut to be carried with the pilot on the return stroke of the press, and means for moving said punch relative to said pilot on the return stroke of the press to strip the nut from the pilot.

13. Apparatus for securing locking washers in elastic stop nuts' comprising a holder adapted to' be secured in the slide of a punch press, a. pilot the bore of the washer on the working stroke of the press, a punch reciprocably mounted in said holder and having a working face for deforming the side walls of the nut inwardly and downwardly.

around said washer on the working stroke of the press after the pilot has passed through the bore of the washer, whereby to compress the washer inwardly against the pilot and to cause fixed in said holder and adapted to pass through the nut to be carried with the pilot on the return stroke of the press, means for moving said punch relative to. said pilot on the return stroke of the pressto strip the nut from the pilot, and means operable after the operation of the last men- 'tioned means for knocking the stripped nu't laterally from the path ofreciprocation of said pilot and punch. a v V L Y 14. In apparatus for forming elastic stop nuts from nut blanks having a non-metallic washer assembled in an open-ended recess in the end oi the bore of the blank, a press-bed for the blank, a slide reciprocable with respect to said bed,

a pilot movable with, said slide and arranged to pass through the bore of said washer on the working stroke, of the slide, a punch movable'with said slide on the working stroke of 'the slide, said'.

punch having a working face] for deforming the side walls of the open end of saidrecess inwardly and downwardly over said washer after said pilot is in the bore of the washer, said punch being reciprocably-mounted relative to said slide, and means associated with said slide for moving said said slide, and an annular punch surrounding said pilot and having a, working position with said pilot projecting beyond the end ofthe punch,

working stroke of said slide before contact of the said pilot entering the bore offsaid washer on'the' working face of said punchwith the blank, and

the'workins face of said M bein formed to turn the side walls of the open end of said recess inwardly and downwardly over said washer at the end of the working stroke of the slide;

16. In apparatus for forming an elastic stop nut from a nut blank having a non-metallic washer assembled in an open-ended recess at one end of the bore of the blank, a resilient press-bed for supporting the blank, a reciprocable slide having a fixed pilot arranged to pass through the bore of the washer on the workin stroke of the slide and an annular punch surrounding said-pilot and having a working face ror deforming the walls of saidrecess inwardly and downwardly over said washer due to end pressure on the blank against said resilient pressbed whereby to secure said washer in said blank with predetermined pressure.

CARL A. SWANSTROM. 

